Not applicable.
Not applicable.
The invention relates to a device for sterilizing water flowing through a sanitary appliance, having
a) a housing, which comprises an inlet and an outlet for the water;
b) a UV lamp, which is disposed inside the housing and the radiation of which is directed towards the water flowing through and optionally towards a filtering apparatus likewise disposed in the housing;
c) a power supply circuit for the UV lamp;
d) a device for producing a switch-on and switch-off signal for the power supply circuit of the UV lamp, which is operationally coupled to a valve lying in the fresh water supply conduit and operable by the user.
In recent years the dangers arising in the field of sanitation from water contaminated with micro-organisms, in particular bacteria, amoebae or other monocellular organisms, have become ever clearer. For said reason, increased importance is being attached to water sterilization. In said connection, there have been reports of experiments to sterilize flowing water through exposure to UV light, which is of a wavelength suitable for killing micro-organisms carried along in the water. To extend the retention time of said micro-organisms in the region of the UV lamp, an additional filtering apparatus may be used.
In the devices known from said experiments, the UV lamp was activated when the water flow is set in operation, e.g. by means of a mechanical switch which was mechanically connected to the operating element of the valve controlling the water flow. Said manner of signalling the request of the user for flowing water was however relatively unreliable, particularly when the valve operable by the user was opened to only a very slight extent.
The object of the present invention is to refine a device of the type described initially for sterilizing water flowing through a sanitary appliance in such a way that the request of the user to remove water and to terminate said removals of water is reliably indicated and may be electronically processed.
Said object is achieved according to the invention in that in the fresh water supply conduit a solenoid valve is disposed upstream of the valve operable by the user and that situated in the fresh water supply conduit between the solenoid valve and the valve operable by the user is a pressure sensor, the signal of which is utilized as a switch-on and switch-off signal of the power supply circuit for the UV lamp and the solenoid valve.
Thus, according to the invention, a mechanical movement at the valve operable by the user is no longer transmitted to an electrical switch. Rather, the pressure in the portion of the fresh water supply conduit lying between the solenoid valve and the valve operable by the user is utilized as a xe2x80x9csensorxe2x80x9d for the request of the user to remove water or terminate the removal of water. A pressure drop in said portion of the fresh water supply conduit is interpreted as an indication that the valve operable by the user has been opened and hence as a request by the user to draw off water. Thus, as soon as such a signal is detected, the UV lamp is switched on and the initially closed solenoid valve is opened. A renewed increase of the pressure in the relevant portion of the fresh water supply conduit is a sign that the user has closed the valve operable by him and therefore no longer wishes to draw off water. In said case, xe2x80x94optionally after a time delayxe2x80x94the UV lamp may be switched off the solenoid valve closed.
Processing of the signal produced by the pressure sensor may be effected xe2x80x9cdirectlyxe2x80x9d in the sense that the actual pressure value is determined and, when it lies below a comparison value, the UV lamp is activated. Thus, for as long as the pressure value lies below the comparison value in question (and optionally for a specific time delay thereafter) the UV lamp is alight. Once the pressure value measured by the pressure sensor rises above the comparison value again (and optionally after a specific delay), the UV lamp is switched off again. With said type of signal processing, therefore, a single passing of the measured pressure value through the comparison value is sufficient to effect a change in the operating state of the UV lamp.
In order to prevent pressure surges, of the type which frequently occur in the fresh water supply conduit of buildings, from leading to misinterpretation of the control electronics, the pressure sensor electronics which process the output signal of the pressure sensor may comprise an integration element, which integrates the output signal of the pressure sensor over a specific period of time, which is longer than the typical duration of pressure surges in the fresh water supply conduit. Such randomly occurring pressure surges, which are generally attributable to the opening and closing of appliances at another point in the building, may in said manner be xe2x80x9caveragedxe2x80x9d and rendered harmless.
A more sensitive electronic processing of the output signal supplied by the pressure sensor may be achieved by providing control electronics, which cyclically open and close the solenoid valve via a valve driver circuit. Said opening and closing operations need not be fully effected; it is frequently sufficient merely to start and then reverse said operations in order to obtain an acceptable signal.
The frequency of said cyclical opening and closing should be between 0.1 and 10 Hz.
The advantage offered by the cyclical opening and closing is that the further processing of the output signal of the pressure sensor may be effected using alternating current techniques. By virtue of the continuous repetition of the signal in question, detection is reliably possible even when the device is at its sensitivity limit.
Particularly preferred is the refinement of the invention, in which the pressure sensor electronics supply the control electronics with a differentiated signal denoting the change of the pressure at the pressure sensor, wherein the control electronics activate the power supply circuit for the UV lamp for the period of time, during which a signal denoting a pressure change, in particular a pressure drop, at the pressure sensor is supplied to them, and optionally for a predetermined period of time thereafter. Said type of signal processing is therefore geared no longer to the absolute value of the pressure, which the pressure sensor measures, but only to the change, in particular drop, of said pressure. So long as during the cyclical opening and closing of the solenoid valve the pressure sensor detects a change, occurring at the same frequency, of the pressure in the portion of the fresh water supply conduit, this means that the valve operable by the user is open, i.e. the user wishes to draw off water. It is only when the valve operable by the user is closed that the pressure prevailing in the relevant portion of the fresh water conduit and measured by the pressure sensor becomes constant in time. Thenxe2x80x94optionally after a specific time delayxe2x80x94the UV lamp may be switched off.
The (at least partial) cyclical opening and closing of the solenoid valve may be. effected continuously. In said case, the pressure prevailing in the relevant portion of the fresh water conduit is continuously xe2x80x9ctopped upxe2x80x9d while the valve operable by the user is closed; leakages, particularly in the valve operable by the user, then do not lead to false tripping of the UV lamp.
Alternatively, it is however also possible for the solenoid valve to be cyclically opened and closed only during the time when the valve operable by the user is open. In said refinement, therefore, the cyclical opening and closing of the solenoid valve serves merely to enable improved detection of the closing of the valve operable by the user. An advantage in terms of detection of the opening of said valve is not provided here. On the other hand, the energy consumption of the device in said case is very much lower because the solenoid valve need be energized only during very much shorter periods of time; the solenoid valve is moreover spared. Said last-mentioned refinement of the signal processing is imperative when the solenoid valve is additionally intended to regulate the water flow, e.g. when the water flow is to start only with a specific time delay after opening of the valve operable by the user.